Puberty blocker trial should be stopped until legal challenge is heard, court told

By SHAUN WOOLLER, EXECUTIVE HEALTH EDITOR Published: 18:50, 27 July 2026 | Updated: 18:52, 27 July 2026 A puberty blocker trial that plans to recruit children as young as 11 should be halted until the outcome of a legal challenge is decided, the High Court has been told. Campaigners want a judge to stop the study from enrolling participants from August 1, arguing that regulators acted unlawfully in approving the experiment. They say proper safeguards were not put in place and they are concerned about the long-term physical and mental side effects on the children involved. Their lawyers today asked the court to make an injunction delaying the start of the trial until the conclusion of the legal challenge. King’s College London, which is leading the proposed trial, is opposing the legal action along with the Health Research Authority (HRA) and the Department of Health and Social Care. The university is also opposing the injunction. Some 226 kids are due to be given drugs to stop their body’s natural development as part of a trial commissioned by former health secretary Wes Streeting. He had indefinitely banned the drugs after the Commission on Human Medicines said they posed ‘an unacceptable safety risk’. Campaigners want a judge to stop the study from enrolling participants from Augus But he backed the Pathways trial into their side-effects, as recommended by the Cass review into the treatment of children who think they are trans. Puberty blockers are hormone-suppressing drugs that pause the physical changes which mark a transition towards adulthood, such as facial hair and periods. The trial has faced criticism surrounding the ethics of giving children a drug that could cause irreversible harm, including to their brains and fertility. The Cass Review recommended the trial after concluding that the quality of research claiming to show the benefits of puberty blockers for youngsters with gender dysphoria was ‘poor’. Transgender children as young as 11 will be able to join after regulators watered down their objections. The launch was dramatically halted in February when the Medicines and Healthcare products Regulatory Agency expressed safety concerns and indicated it wanted to restrict the trial to kids aged 14 and over. But researchers revealed last month that they will resume recruitment from August 1 after officials agreed to the lower age threshold. Angus McCullough KC, for the campaigners, said in written submissions for today’s court hearing that the trial would involve children under the age of 16-years-old, half of which would begin the treatment straight away while half would start it a year later. Some 226 kids are due to be given drugs to stop their body’s natural development as part of a trial commissioned by former health secretary Wes Streeting (pictured). The barrister said: ‘A short delay to the trial of three to four months will cause the least irremediable prejudice to the safety and interests of its potential child participants, which is the overwhelming consideration, compared to starting and then suspending the trial.’ Mr McCullough also said the legal challenge should continue because proper safeguards were not followed when designing the trial. He told the court: ‘However compelling the scientific need for a clinical trial may be, arising from that dearth of reliable evidence, that cannot displace the safeguards embedded in the regulations for the protection of child participants in a proposed clinical trial.’ The campaigners bringing the court case are Bayswater Support Group, which is made up of parents and guardians of children and young adults who identify as trans or non-binary, as well as psychotherapist James Esses and Keira Bell, who began taking puberty blockers when she was 16 before later ‘detransitioning’ and who has spoken of the long-term effects such treatments had on her. Julian Milford KC, for the Government, said the challenge was a ‘straight disagreement’ with how the Medicines and Healthcare products Regulatory Agency (MHRA) balanced the benefits and risks. In written submissions, he said: ‘The MHRA recognised that for many trial participants, much of the benefit of taking puberty suppressing hormones might consist in the fact that it would allow them in due course to transition gender through the use of masculinising and feminising hormones – where clinically appropriate – before they had developed the secondary characteristics of their birth sex.’ Jenni Richards KC, for the HRA, said in written submissions that a suggestion that a research ethics committee did not consider the trial group to have any direct benefits from the study is ‘unarguable’. She said the eligibility criteria for participation in the trial require that the young person’s clinician believes the young person has a ‘reasonable prospect of benefiting’, if they were to try puberty suppressing hormones. Andrew Sharland KC, for King’s College London, added to the Government’s argument that the aim of the trial is to investigate the benefits and risks of taking the hormones. He said: ‘The claimants complain that it is not possible, before the trial begins, to identify which individual participants will benefit. 'That is not a flaw in the trial - it is the premise on which the trial is ethically and scientifically justified. ‘Pathways proceeds in a state of genuine clinical and scientific uncertainty about the short- and medium-term benefits and risks of GnRHa for this patient group.’ The hearing, before Mr Justice Chamberlain, is due to conclude tomorrow.